Wound canister waste solidification system

ABSTRACT

The invention includes a negative wound therapy system including a container, a wound covering, a packet and a plurality of surface cross-linked superabsorbent particles. The invention may be portable. The invention also includes a liquid solidification system for reducing gel block in NPWT systems. Methods of solidifying liquid medical waste from NPWT devices are also described and disclosed.

This application is a Continuation of U.S. application Ser. No.14/202,377, filed Mar. 10, 2014, which claims the benefit of U.S.provisional application No. 61/776,242, filed Mar. 11, 2013, which areincorporated herein by reference in their entireties.

BACKGROUND

This disclosure relates generally to portable negative pressure woundtherapy systems and methods for treating a wound and more specifically,an improved wound canister waste solidification system.

Wound healing is known to present challenges within the medical field.In order for a wound to close, epithelial and subcutaneous tissuesaround the wound migrate and progress towards the center and away fromthe base of the wound until the wound closes. Closure is especiallydifficult with larger wounds, chronic wounds or wounds that have becomeinfected. A zone of stasis (area in which localized swelling of tissuemay restrict blood flow to the tissues) may form near the surface of awound, preventing tissues from receiving adequate oxygen and nutrientsand inhibiting the ability to resist microbial infection and affectproper wound healing.

Negative pressure wound therapy (NPWT), also known as suction or vacuumtherapy, has been used and found beneficial in treating and healinglarge or difficult wounds. Applying negative pressure to an area over awound has been found to promote closing of the wound due to promotion ofblood flow to the area, stimulation of the formation of granulationtissue and encouragement of the migration of healthy tissue over thewound. Fluids may also be drawn from the wound by using negativepressure and thus remove fluids that would otherwise tend to encouragebacterial growth. Particularly, this negative pressure therapy has beenrecognized as effective for chronic, healing-resistant andpost-operative wounds.

Typically, in NPWT, a wound covering is positioned over a wound. Anattachment in communication with a vacuum source, such as tubing, isadded to the wound covering and facilitates suction at the wound site.Fluids and exudates drawn off the wound site through the tubing areusually transferred to and stored in a waste storage container.

Often, it is in the best interest of a patient to remain ambulatory ifpossible. In such circumstances, portable NPWT devices may be prescribedfor a patient with a wound. Portable NPWT devices are typically largeand have attachments, such as a control unit, including a suction pumpand electronic monitor, for example, microprocessors or pressuretransducers. It is recognized that NPWT devices are prone to tippingand/or leakage at the container and around the wound covering,especially when portable NPWT units are worn and patients move around.This produces several problems, however. For example, the exudates mayaspirate from the container and clog the attachment, damage theelectronics and pump and/or leak from the container and expose thepatient to biological wastes and contaminants. To address theseproblems, some have attempted to provide improved tubing, while othershave increased the pump strength and/or improved the seal made by thewound covering at the wound site. Screens, filters and seals have beenadded to NPWT systems in an attempt to prevent leakage of waste fluidsfrom the waste storage container and backflow into tubing, control andnegative pressure sources. Absorbents have even been added to containersin an attempt to limit the liquid available to spill or leak. Theabsorbents, typically used, however, do not reach full solidification ofthe fluids for many reasons. Some absorbents can also be caustic andmust be very carefully handled by patients and medical personnel inorder to avoid exposure. Despite these attempts to prevent potentialharmful exposure, leakage of biological wastes and potentially harmfulbacteria, fungi or other organisms remains a problem. The potential forspillage of these contaminants may inhibit patients from utilizingportable NPWT devices and/or prolong a hospital stay due to a wound.Home use of NPWT is discouraged when patients would have to tend to thedevice and contamination exposure remains a real threat. As a result,hospital stays may be prolonged unnecessarily and medical costsincreased. It is to these and other problems that this disclosure isdirected.

SUMMARY OF THE INVENTION

The invention of the present disclosure fulfills one or more of theseneeds in the art by providing in one embodiment a portable negativepressure wound therapy system including a container, a wound covering, apacket able to be housed within the container and a plurality ofsuperabsorbent particles enclosed within the packet and releasable upondissolution of at least a portion of the packet in aqueous liquid. Thecontainer is operable to receive fluid from a wound site. The containeris also in communication with a vacuum tube. The vacuum tube connects toa control having a negative pressure source. The wound covering connectsto the vacuum tube so that the negative pressure source is able to exerta negative pressure on the wound site through the covering when thecovering is applied to the site. The packet is at least partiallysoluble in an aqueous liquid.

Additionally, the system may include a sanitizer. The sanitizer may begranular chlorine and/or any other agents that destroy bacteria, fungi,viruses and/or related organic matter.

Another embodiment includes a system for solidification of liquidmedical waste for use in connection with aqueous liquid to be solidifiedfrom a NPWT device. In one example, the system includes an absorbentcomposition and a packet enclosing the absorbent composition. Theabsorbent composition is granular and includes a plurality of surfacecross-linked superabsorbent particles. The absorbent composition mayadditionally include a plurality of second particles. The packet is atleast partially soluble in the aqueous liquid to be solidified so thatthe absorbent composition is released upon dissolution of the packet.The packet may be made of dissolvable polyvinyl alcohol and/or thepacket may include only a dissolvable portion.

In another embodiment, a liquid solidification system for reducing gelblock in a NPWT system includes a packet and a solidifier. The packet isconfigured to allow liquid penetration. The solidifier is initiallylocated within the packet and includes a plurality of surfacecross-linked superabsorbent polymer particles. A plurality of secondparticles may also be included. Liquid flow channels are defined betweenthe superabsorbent polymer particles. Second particles may also act asspacers to provide flow channels.

The invention can also be considered as a solidification method for NPWTwaste fluids including the steps of connecting a container operable toreceive fluid from a wound site with a NWPT device; having the containerin communication with a vacuum tube; providing a negative pressuresource; allowing a wound covering to connect to the vacuum tube so thatthe negative pressure source is able to exert a negative pressure on thewound site through the covering when the covering is applied to thesite, and including a packet in the container to be housed within thecontainer, the packet being at least partially soluble in an aqueousliquid and having a plurality of surface cross-linked superabsorbentparticles enclosed within the packet that are releasable upondissolution of at least a portion of the packet in the aqueous liquid.

The method may also include housing sanitizer along with the particlesinside the packet. In another example, a method of solidification forNPWT systems includes: selecting a portion of cross-linkedsuperabsorbent particles that maintain a state of permeability uponsolidification, determining the portion based upon a volume of liquidwastes to be solidified within a NPWT container during a NPWT treatment,and housing the portion inside an at least partially soluble packet.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood by a reading of the DetailedDescription of the Examples of the Invention along with a review of thedrawings, in which:

FIG. 1 is a perspective view of one example of a portable negativepressure wound therapy system;

FIG. 2 is a side view of one example of a container of the portablenegative pressure wound therapy system according to FIG. 1;

FIG. 3 a another side view of one example of a container including apacket;

FIG. 4 is a perspective view of one example of a packet of the portablenegative pressure wound therapy system according to FIG. 1; and

FIG. 5 is a perspective view of another example of a negative pressurewound therapy system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In hospitals, collection of liquid medical waste is regulated and mustbe solidified prior to being transported and/or discarded. Evenhospitals struggle to adequately solidify liquid wastes, such as thoseoften gathered during surgery, in order to meet regulation and preventpatient and personnel exposure. Many waste solidifiers are contained inbottles and the solidifier must be accurately measured, depending on theamount of the waste fluids, and then administered to a waste vesselafter the fluids are collected. Exposure during application of thesolidifier, complicated measurements, inadequacy of the solidifiers andinconvenience prevents these hospital solidifiers from successfullybeing used in negative pressure would therapy, particularly portable andhome NPWT.

Further, when using solidifiers for solidifying liquid wastes, reachingfirm solidification is necessary so no fluids will spill when thecontainer is turned on its side. Otherwise, some of the waste issolidified, while a portion remains liquid and prone to spillage, andprovides a false sense of security and a potential health and safetythreat to the operator.

“Gel block” is recognized as a problem with solidifiers, particularlywhen solidifier is added to a container prior to the collection of thewastes, in an attempt to limit or prevent contaminant exposure afterwastes are present in the container. Development of gel block prohibitsfirm solidification of liquids. Gel block occurs when an inflowingaqueous mixture reaches some of the solidifier and becomes solidifiedbut then the solidified waste sections off portions of the fluid so thatit cannot reach remaining available solidifier (where portions of theliquid and available solidifier are unable to come into contact witheach other), essentially creating a “block” to firm solidification. Whengel block occurs, the aqueous fluid does not firmly and completelysolidify, and spillage during transport or movement is problematic.Previously, the problem of gel block has been addressed in a variety ofways. Various solidifiers with different densities have been combined sothat the solidifier will migrate to specific levels or zones of thefluid. However, weighted solidifiers take some time to reach theirseparated levels, and the use of swifter solidifiers with a NPWT systemstill presents problems with gel block. Additionally, the speed withwhich the fluid is introduced and the timing of the release of weightedsolidifier is extremely important if the weighted solidifier is toinhibit gel block. Very quickly introduced and/or small amounts of fluidintroduced over a longer period of at least an hour and fluidintroduction persisting for hours and days increases the problems withgel block occurrence.

Absorbents contained within burstable paper pouches have been used andmay actually intensify gel block in some instances because enough watermust slowly seep through the pouch and create enough expansion withinthe absorbents to rupture the bag before the absorbent is released intothe entire waste container environment. The release of absorbents inthis scenario can be unpredictable and unreliable. While certainsolidifiers may suffice to solidify liquid wastes during hospitalprocedures, such as surgeries, Applicant realized that NPWT treatmentstypically extends over a longer period of time than finite hospitalprocedures and usage of solidifiers with NPWT systems includedadditional challenges. With these types of recognized problems occurringwith the use of solidifier in quickly disposed biological wastecontainers, solidifier for use in patient controlled collection devicesis even more problematic, especially when solidifier needs to solidifysmall amounts of fluids gathered over longer periods of time, at leastan hour and perhaps days or even months. Applicant's invention addressesthese and other such problems and needs in the art.

Superabsorbent polymers, such as that disclosed in U.S. Pat. No.7,291,674 to Kang, which is herein incorporated by reference in itsentirety, are known as water-swellable, water-insoluble, organic orinorganic material capable of absorbing at least about 100 times itsweight and up to about 300 times its weight in an aqueous solution.Superabsorbent polymers are cross-linked, neutralized polymers which arecapable of absorbing large amounts of aqueous liquids and body fluids,such as urine, wound exudates or blood, with swelling and the formationof hydrogels, and of retaining them under a certain pressure inaccordance with the general definition of superabsorbent. The main usefor internally cross-linked superabsorbent polymers, however, has beenin sanitary articles, such as diapers. The trend in sanitary articles,for comfort and sanitation reasons, has been to make them smaller andreduce their size. To do this, much of the fluff fiber in these articleshas been removed and more superabsorbent polymer has been added. Withless structure provided, more superabsorbent polymer is needed insanitary articles along with a higher gel strength. However, increasinggel strength in cross-linked superabsorbent polymers often results inless polymer swellability, permeability and retention capacity. The Kangpatent addresses surface cross-linking superabsorbent polymers in orderto maintain liquid retention, permeability, and, particularly gel bedstrength under pressure, when superabsorbent polymer is increased inpercent by weight based on the dry absorbent structure.

Applicant realized that surface cross-linked superabsorbent polymercould be developed and used in aqueous environments, such as biologicalwaste containers, where permeability and liquid solidification are themain objectives and not particularly gel bed strength. Applicant hasdiscovered that the use of the superabsorbent polymer in NPWT systemsprevents development of gel block and addresses the problems associatedwith NPWT devices, particularly when patients move around, have aportable NPWT device, and/or are considered for patient use outside of ahospital.

Referring now to the drawings in general, the illustrations are for thepurpose of describing a preferred example of the invention and are notintended to limit the invention thereto. NPWT devices are generallyknown in the art. One benefit of Applicant's invention is that itinhibits free waste liquid available for spillage in a manner compatiblewith many, if not all, NPWT devices that shuttle the biological waste toa storage container. This is true particularly for portable NPWTdevices. FIG. 1 shows one example of a portable negative pressure woundtherapy system, generally referred to as 10, including a container 12operable to receive fluid from a wound site 14, a negative pressurevacuum source 26, a wound covering 16 connecting to a vacuum tube 20, apacket 22 and a plurality of surface cross-linked superabsorbentparticles 24 enclosed within the packet.

The container 12 is operable to receive fluid from a wound site and istypically in communication with a vacuum tube 20. FIGS. 2 and 3 showside views of an example container. The container may include a lid 26.The container may have a compartment for storage of exudate and/or theentire container may serve as a storage compartment. Exudate andbiological waste as used herein, generally refers to any fluid outputfrom a wound, such as but not limited to, blood, serum, pus, biologicalcontaminants, biological organisms, irrigation fluids, and/or smalltissues contained within the fluids. The container may existindependently of the other NPWT devices, or it may incorporate withother NPWT devices, as seen in FIG. 5 where the container 12 fitsremovably onto the pump. The vacuum tube typically connects to a vacuumcontrol having a negative pressure source 26, for example, a vacuumpump, such as a peristaltic pump, a diaphragmatic pump or amini/micro-pump. The exudate from the wound is directed through a vacuumtube and deposited in the container. The term “tube” refers to anyconduit or passageway that is suitable for transporting the exudate tothe container. The container may take on variable sizes and shapes. Forexample, the collection container may be rigid or a semi-rigid plasticcontainer or may be a polymeric pouch.

The wound covering 16, one example of which is described in U.S. Pat.No. 8,257,328, which is herein incorporated in its entirety, istypically connected to the vacuum tube 20 so that the negative pressuresource 26 is able to exert a negative pressure on the wound site 14through the covering when the covering is applied to the site. Woundcoverings may have different dimensions to accommodate different wounds.Typically, the wound coverings are applied to the wound and sealed tocreate a sealed wound dressing. The dressing may include, by way ofexample, a port assembly, an open-cell foam wound covering, dressingsand gauze, often sealed with an occlusive dressing to allow a vacuum topersist at the wound site. Dressings may also include wound cover layersand wound fillers. Wound covers may be removed from connection with thevacuum tube so that the dressing may be changed. The wound coveringand/or dressing may be changed while the remainder of the NPWT systemremains in place. The new wound covering may be reattached to the vacuumtube and the NPWT treatment resumed. It is not uncommon for woundcoverings and/or entire wound dressings to need to be changed two tothree times per week.

The packet 22 is able to be housed within the container 12 and is atleast partially soluble in an aqueous liquid. The plurality of surfacecross-linked superabsorbent particles 24 are enclosed within the packet22 and releasable upon at least partial dissolution of at least aportion of the packet in aqueous liquid. FIG. 4 shows examples of apacket 22 enclosing superabsorbent polymer particles 24. The packet 22typically is placed inside of container 12 before a negative therapywound pressure treatment is begun, however, may be added afterwards. Inone example, the packet 22 is made of dissolvable polyvinyl alcohol;however, the packet made be made of any suitable water soluble film. Thepacket may be partially made of a paper type material and have adissolvable portion. The dissolvable portion of packet 22 should havedisintegration time and temperature suitable to the fluids in which itwill be exposed. Another consideration is compatibility of the packet 22with its contents. Packet 22 should provide for prolonged storagecapacity without resulting in insolubility, rigidity or changes inpacket 22 or its contents. Examples of such compatible packets 22 aredissolvable films that can be acquired from MonoSol, LLC, such as theirmodels M7031, M7061, M8534, and M8900 (PXP6829) of water soluble film.Optionally, water soluble paper may be used. Packet 22 may be madeentirely of a dissolvable packet, partially of a water soluble/permeablepaper or may include a dissolvable portion. The dissolvability of packet22 allows packet 22 to be placed into container 12 prior to introducingfluids into the container. The dissolvable packets 22 provide a costeffective way to eliminate risk of exposure for medical workers and/orpatients and prevent excessive handling of the solidifier, container 12or lid 26, either before or after fluids have been introduced and whilethey are still liquid. Such handling is necessary with powder or looseabsorbents. Since the packet protects and can supply superabsorbentpolymer particles to firmly solidify the exudate in the container,without the patient or personnel opening the container after thetreatment has begun, then leakage or exposure becomes much less likelyfor NPWT devices, and portable and/or home NPWT devices. Additionally,firm solidification of the wastes minimizes the available fluid wastesthat are able to seep out of the container and into the pump orcontroller, potentially damaging the most expensive parts of the NPWTsystem. A packet 22 may also be included within a container 12 prior totreatment and one side of the packet adhered to an interior portion ofthe container to maintain placement of the package. Any suitableadhesive or tape may be used that is compatible with the packet.

Enclosed within packet 22, shown in FIGS. 1 and 4, is a quantity ofsurface cross-linked superabsorbent particles 24, for example, SodiumPolyacrylate Polymer. Cross-linked superabsorbent particles areinternally and surface cross-linked superabsorbent polymers. A suitablesuperabsorbent polymer may be selected from natural, biodegradable,synthetic and modified natural polymers and materials. The termcrosslinked used in reference to the superabsorbent polymer refers toany means for effectively rendering normally water-soluble materialssubstantially water-insoluble but swellable. Such a crosslinking meanscan include for example, physical entanglement, crystalline domains,covalent bonds, ionic complexes and associations, hydrophilicassociations such as hydrogen bonding, hydrophobic associations or Vander Waals forces. Superabsorbent polymers have one or both of internalcrosslinking and surface crosslinking. Surface crosslinking is anyprocess that increases the crosslink density of the polymer matrix inthe vicinity of the superabsorbent particle surface with respect to thecrosslinking density of the particle interior. Surface cross-linkedsuperabsorbent polymers of the present disclosure are available, forexample, from Stockhausen, Inc. of Greensboro, N.C. or from Zappa Tec,LLC of McLeansville, N.C., as AP95.

In one example, after packet 22 with an enclosed polymer and/or polymercomposition is placed inside container 12, then fluid 26 may beintroduced without reopening or accessing the container. As liquid basedbiological waste is introduced into the container 12, packet 22dissolves, releasing the solidifier. The solidifier 24 scattersthroughout the aqueous liquid waste and the superabsorbent particlesfirmly solidify the liquid. The granular solidifier/composition becomesa gel-like substance as it solidifies the liquid. Due to the increasedand maintained permeability of the superabsorbent polymer particlescontained within the packet, fluid that arrives in container 12, evenslowly over long periods, for example as a patient wound is treated overhours, days or weeks, is continually solidified. The packet housing thesuperabsorbent particles allows safe and effective pre-introduction ofthe solidifier before waste enters the container and prohibits gel-blockdue to maintained permeability of the superabsorbent particles even whena portion of the gel is already formed. The container for the NPWTsystem may even come pre-equipped with the solidifier packet alreadyinside and potentially sealed, minimizing steps performed by the medicalpersonnel and/or patient. The container may be disposable once fluid issolidified in the container over time and replaceable with anothercontainer having a solidifier packet for continued treatment to enhancesterile environments and safety for the patient.

A plurality of second particles may be combined with the superabsorbentpolymer particles to make a solidification composition. The plurality ofsecond particles may be inorganic, water-insoluble particles. In oneembodiment, second particles may be hydrophilic fumed silica as isoffered by Evonik Industries as AEROSIL® 200. While not the preferredembodiment, other additives such as silicates, kaolin, zeolites andbentonite may be used.

The plurality of second particles 18 may reside on the surface of thesuperabsorbent particles and become substantially interspaced betweenthe superabsorbent particles. Second particles may be attracted to thesuperabsorbent particles by electrostatic forces. In some examples, thesecond particles may allow fuller and quicker liquid absorption by thesuperabsorbent particles by inhibiting full surface touching of thesuperabsorbent particles with one another. Additionally, the secondparticles may reduce attractive forces between the superabsorbentparticles and reduce the likelihood of a film developing betweensuperabsorbent particles that would inhibit permeability. Due to thepresence of the second particles and the surface cross-linking of thesuperabsorbent particles, liquid flow channels may be maintained for alonger period of time between the superabsorbent particles. Thus,permeability of the gel is high as fluid is able to flow between thesuperabsorbent particles in the liquid flow channels, even after theparticles begin to swell. Additionally, swellablity of thesuperabsorbent particles is increased due to the presence of the secondparticles. The liquid flow channels allow fluid to permeate the gel andflow to dry superabsorbent particles, thus further reducing the chanceof occurrence of the previously known problem of gel block in theprocess of solidification of liquid medical wastes.

The absorbent composition may include superabsorbent polymer particlesand a sanitizer. Adding a sanitizer assists in further neutralizing thecontaminants in the liquid medical waste, reducing handling risk. Anysuitable granular sanitizer may be used. The sanitizer, by way ofexample, may be sodium dichloro-s-triazinetrione dihydrate known as ACL®56 Chlorinating Composition and available from OxyChem® of Texas. Theabsorbent composition reduces the chance of gel block and inadvertentexposure to hazardous bio-contaminants by allowing solidificationwithout the need to interact with the inside of container 12 once a NPWTtreatment begins. The sanitizer further minimizes exposure byneutralizing bio-contaminants within the waste fluid and solidified gel.The sanitizer that is added may be any suitable agent that destroysbacteria, fungi, viruses, organic matter and/or waste contaminantswithout interfering with the packet integrity and the solidifier.Dissolvable films were tested to determine example dissolvable packsthat maintain proper functionality with the addition of the sanitizer.Similar considerations as discussed above for the dissolvable film packswould apply here as well. The sanitizer creates a different chemicalenvironment within the packets and may cause greater instability overtime in the packets typically used for housing superabsorbent particlesalone. Other examples of compatible packets for use with superabsorbentparticles mixed with sanitizer are dissolvable films that can beacquired from MonoSol, LLC, such as their models M7031 and M8900(PXP6829) of water soluble film. Another packet material able tosuitably accommodate the addition of a sanitizer to the packet is, theGA40 film manufactured by Aicello American Corporation. Through testing,Applicant has determined that this film is effective for use with thesuperabsorbent particles and sanitizing agents.

Another factor that has minimized the use of NPWT devices both inhospitals and with portable devices at home is the odor that canaccompany the treatment. Filters have been tried and occasionallycharcoal additives included in the container. The exudate collected incollection vessels during a NPWT treatment can provide a breeding groundfertile for growth of biological organisms, such as bacteria. Theexudate and the biological organisms themselves can either and/or bothcreate an extremely odorous byproduct environment that makes the use ofNPWT devices extremely unpleasant. The odor can increase over time andbecome intolerable, especially in NPWT treatments that, not uncommonly,last for hours, days, weeks or longer. The addition of the sanitizer tothe superabsorbent polymer particles not only disinfects the exudate,reducing odors, but also prohibits development of a biological organismbreeding ground within the container 12. Alternatively, disposing of thecontainer once in use for a period and continuing the treatment withfresh container may assist with sanitation and odor control for thepatient.

Additionally, this invention may be a liquid solidification system forreducing gel block in negative pressure wound therapy treatment systems,including a NPWT device, a packet and a liquid solidifier. The packetmay be entirely dissolvable in fluids or may contain a dissolvablesection. The liquid solidifier includes a plurality of surfacecross-linked superabsorbent polymer particles that maintain fluidpermeability during solidification of waste fluids. The packet mayoptionally be a bottle or any other suitable type of container. Thesystem may include a sanitizer. The system may include a population ofsecond particles.

As many medical treatments are, wound care and NPWT can be expensive.Therefore, it is beneficial if the treatments can be made more effectivewith less waste of supplies and increased safety. Applicant's inventionminimizes the amount of solidifier necessary to reach firmsolidification of the waste in a container and also minimizes the needto change out the container more often. While it is a benefit ofApplicant's invention to be able to have the solidifier contained andprotected in the packet and to be added before the treatment begins, itis also possible to begin with minimal determined amounts of solidifierand add more in additional packets if more fluid than originallyprojected is collected, or if the treatment needs to proceed longerwithout interruption. Particularly in portable and home use NPWTdevices, as little as about 5 to 9 grams of superabsorbent polymerparticles may be placed in packets and used for solidification of theentire volume of the waste container. Variable amounts of polymer may beallocated depending on the volume and usage. Packets can be fittedaccordingly.

In other examples, 5 to 22 grams or more of superabsorbent particles maybe packeted. Typically, the liquid solidification system proportionallymay include about 20 grams of the superabsorbent polymer particles per1000 cc of fluid to be solidified. By weight/weight % a ratio of about0.5% to 1.5% of the second particles per the superabsorbent polymerparticles, preferably 1% second particles may be added.

In one example, the system may include between 20 and 40 grams of thesuperabsorbent polymer particles per 1000 cc of fluid to be solidified.Additionally, the liquid solidification system may further include byweight/weight %, a ratio of about 5% to 15% of sanitizer persuperabsorbent polymer particles, preferably 10%. When the sanitizer isadded to the liquid solidification system, the system may include anadditional by weight/weight % a ratio of about 10% to 20% ofsuperabsorbent polymer particles to the original grams of superabsorbentpolymer particles. The additional superabsorbent polymer was found to bebeneficial to the solidification process when the sanitizer was added toensure firm solidification in the presence of the sanitizer.

The invention may further be a method of solidifying liquid medicalwaste in a negative pressure wound therapy system comprising the stepsof: housing a population of cross-linked superabsorbent polymerparticles in a dissolvable film packet; sizing the packet to fit withina container; including an amount of particles in the populationsufficient to solidify the volume of liquid accommodated by thecontainer.

Prior systems and methods of releasing superabsorbent polymer, includinginternally cross-linked superabsorbent polymer particles, have beenfound to suffer from gel block due to the rapid swelling of theparticles. Gel blocking occurs when the body of the absorbent forms abarrier layer of gel that keeps further liquid from contacting dryabsorbent on a side of the gel away from the liquid. Such gel blockingmay prevent the complete absorption of the liquid since the liquid to beabsorbed is kept away from the dry absorbent by the gel barrier. Surfacecross-linked superabsorbent polymers have been found to increase thestrength of the polymer-gel in sanitary articles such as diapers;however, increasing gel strength often decreases permeability,swellability and retention capacity of the superabsorbent polymer. Whilesuccessfully applied in sanitary articles, absorption of medical fluidshas the additional concern of gel block.

At the end of or during a NPWT procedure where liquid medical waste isgathered, the contents are turned into a firm gel, and the container canbe disposed of sanitarily with less of a threat of spillage or patientand/or personnel exposure. Typically, the container 12 with its gelledwaste contents is disposed of as a standard biohazard, without openingthe container 12. Post-procedure cleanup is streamlined, sanitary andtime saving. The liquid solidifier in the packet is a much moreefficiently packaged product as it is durable and easy to handle.Without bottles or solidifier to keep safe outside of the containerprior to treatment, no excess solid waste is generated and storagecapacity is minimal. However, as previously discussed, use of theparticle combinations dispensed from bottles or other containers iswithin the scope of the invention.

The particle and packet combination provides full solidification,irrespective of how quickly fluid is introduced.

The particle combination inhibits the formation of gel block prior tofirm solidification.

The particle combination reduces the time and risk of adding solidifierafter waste fluid is introduced and the time and risk involved with postprocedure handling.

The particle combination as packaged in the packet saves on storagespace.

The packet and particle combination, along with sanitizer, minimizes theodor and risk associated with NPWT waste collection.

Certain modifications and improvements will occur to those skilled inthe art upon reading the foregoing description. It should be understoodthat all such modifications and improvements have been omitted for thesake of conciseness and readability, but are properly within the scopeof the following examples. For example, although the primary intendeduse is for liquid medical waste, other aqueous liquids could besolidified. Also, although the film is preferably all dissolvable, it iswithin the scope of the invention to make only parts dissolvable.

I claim:
 1. A disposable negative pressure wound therapy wastecollection system comprising: a container operable to receive fluid froma wound site and in communication with a vacuum tube, wherein the vacuumtube connects to a vacuum control having a negative pressure source, awound covering connecting to the vacuum tube so that the negativepressure source is able to exert a negative pressure on the wound sitethrough the covering when the covering is applied to the site, a packetable to be housed within the container, the packet being at leastpartially soluble in an aqueous liquid, and a plurality of surfacecross-linked superabsorbent particles enclosed within the packet andreleasable upon dissolution of at least a portion of the packet in theaqueous liquid, wherein the plurality of the surface cross-linkedsuperabsorbent particles maintain permeability and prohibit gel-block ofthe aqueous liquids when the aqueous liquids are introduced slowlywithin the container over a period of at least an hour.
 2. The system ofclaim 1, including second particles.
 3. The system of claim 2, whereinthe second particles are inorganic non-soluble particles.
 4. The systemof claim 3, wherein the second particles are fumed silica.
 5. The systemof claim 1, further including a sanitizer.
 6. The system of claim 5,wherein the sanitizer is granular chlorine.
 7. A system forsolidification of liquid medical waste for use in connection with acontainer configured to receive an aqueous liquid from a NPWT device tobe solidified comprising: an absorbent composition, the absorbentcomposition being granular and including a plurality of surfacecross-linked superabsorbent particles surface cross-linked to maintainpermeability and configured to prohibit gel-block during theintroduction of aqueous liquids, and a packet enclosing the absorbentcomposition, the packet being at least partially soluble in the aqueousliquid to be solidified so that the absorbent composition is releasedupon dissolution of the packet, wherein the aqueous liquids are slowlyintroduced into the container over a time period into a patientcontrolled collection device and the absorbent composition is configuredto maintain a firm solidification over the entire period of time thatfluids are collected and introduced into the patient controlledcollection device.
 8. The system for the solidification system of claim7, including a wound covering and a negative pressure source.
 9. Thesystem for solidification as claimed in claim 8, wherein the packet ismade of dissolvable polyvinyl alcohol.
 10. A Negative Pressure WoundTherapy solidification system for reducing gel block, the systemcomprising: a container for collecting liquid wastes entering thecontainer over a time period of at least an hour; a packet configured tofit within the container and to allow a liquid penetration; and asolidifier for liquids that is initially located within the packet, thesolidifier comprising: an amount of a superabsorbent polymer particlesto firmly solidify the volume of liquid wastes able to be held by thecontainer, wherein a plurality of liquid flow channels maintainpermeability to allow for firm solidification of the volume of fluidheld by the container.
 11. The liquid solidification system of claim 10,wherein the solidifier for liquid further includes by weight/weight %, aratio of about 0.5% to 1.5% of a portion of second particles.
 12. Theliquid solidification system of claim 10, further including byweight/weight % ratio of about 5% to 15% of sanitizer.
 13. The liquidsolidification system of claim 12, wherein a plurality of liquid flowchannels maintain permeability to allow for firm solidification in under5 minutes.
 14. The liquid solidification system of claim 10, wherein aplurality of liquid flow channels maintain permeability to allow forfirm solidification of the volume of fluid held by the container at arate chosen from 5 to 10 minutes.
 15. A solidification method forNegative Pressure Wound Therapy waste fluids comprising: including acontainer operable to receive fluid from a wound site and incommunication with a Negative Pressure Wound Therapy device, having thecontainer in communication with a vacuum tube, providing a negativepressure source, allowing a wound covering to connect to the vacuum tubeso that the negative pressure source is able to exert a negativepressure on the wound site through the covering when the covering isapplied to the site, and including a packet in the container to behoused within the container, the packet being at least partially solublein an aqueous liquid and having a plurality of surface cross-linkedsuperabsorbent particles enclosed within the packet that are releasableupon dissolution of at least a portion of the packet in the aqueousliquid, selecting the surface cross-linked superabsorbent particles tomaintain permeability and prohibit gel-block during introduction of thewaste fluids over the course of a Negative Pressure Wound Therapytreatment such that the waste fluids entering the container are firmlysolidified.
 16. The method of claim 15, including a sanitizer housedalong with the particles inside the packet.
 17. A method ofsolidification for Negative Pressure Wound Therapy (NPWT) systemscomprising: selecting a quantity of cross-linked superabsorbentparticles that maintain a state of permeability upon solidification andduring the introduction of the aqueous liquids over an entire period oftime during which the cross-linked super absorbent particles remain inthe NPWT system, determining the quantity based upon a volume of liquidwastes to be solidified within a NPWT container during a NPWT treatment,encasing the quantity inside an at least partially water soluble packet,and sizing the water soluble packet to fit inside the NPWT container.18. The method of claim 17, including providing a quantity ofcross-linked superabsorbent particles adapted to achieve firmsolidification of liquid wastes.
 19. The method of claim 18, includinghousing sanitizer along with the quantity of particles inside thepacket.
 20. The method of claim 18, including allowing firmsolidification of gathered fluids entering the container in a patientcontrolled collection device for a NPWT treatment.